Safety laminates have been in commercial production for almost a century and have been utilized in applications that require sheet material having a high degree of clarity and impact resistance. For example, safety laminates have been widely used in the automobile industry as windshields or side windows because the laminate structures are characterized by high impact and penetration resistance and do not scatter glass shards and debris when shattered. More recently, safety laminates are also being incorporated into building structures as windows, walls, stairs, etc.
Safety laminates typically consist of a sandwich of two glass sheets or panels bonded together with an interlayer of a polymeric sheet. One or both of the glass sheets may be replaced with optically clear rigid polymeric sheets, such as sheets made of polycarbonate. Safety glass laminates have further evolved to include multiple layers of glass and polymeric sheets bonded together with interlayers of polymeric sheets.
The interlayers used in safety laminates are typically made from relatively thick polymer sheets, which exhibit toughness and bondability to the glass in the event of a crack or crash. Widely used interlayer materials include complex, multicomponent compositions based on poly(vinyl butyral), poly(urethane), ethylene vinyl acetate copolymers and ionomeric ethylene carboxylic acid copolymers (such as ionic, partially or fully neutralized ethylene methacrylic acid copolymers and ionic, partially or fully neutralized ethylene acrylic acid copolymers (i.e. ethylene methacrylic acid copolymer ionomers and ethylene acrylic acid copolymer ionomers)).
Blend compositions of ethylene copolymers, such as those disclosed in U.S. Patent Publication Nos. 2006/0025527, 2006/0160952 and 2006/0148988, have been found to exhibit high temperature resistance and good high frequency weldability. In addition, the blend compositions can adhere well to metals (such as aluminum) or plastics (such as polyamides and polyolefins). However, it has been found, that polymeric sheets made from such ethylene copolymer blends can also form superior adhesive bonds to glass, and that such adhesive bonds are water resistant.